Ecosystem Ecology. I. Introduction - Ecosystem: an assemblage of organisms, together with their...

Ecosystem Ecology

Ecosystem Ecology

I. Introduction

- Ecosystem: an assemblage of organisms, together with their chemical and physical environments

Ecosystem Ecology

I. Introduction

II. Energy Flow

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

1. Gross Primary Productivity

Total photosynthetic productivity:

CO2 + H20 -----> Glucose + O2

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

1. Gross Primary Productivity

Total photosynthetic productivity:

CO2 + H20 -----> Glucose + O2

Metabolism

Growth

Reproduction

1. Gross Primary Productivity

Total photosynthetic productivity:

CO2 + H20 -----> Glucose + O2

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

2. Net Primary Productivity:

- energy stored in biomass

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

2. Net Primary Productivity:

- energy stored in biomass

- measurements

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

2. Net Primary Productivity:

- energy stored in biomass

- measurements

- factors affecting NPP

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

2. Net Primary Productivity:

- energy stored in biomass

- measurements

- factors affecting NPP

- light

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

2. Net Primary Productivity:

- energy stored in biomass

- measurements

- factors affecting NPP

- light

- water

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

2. Net Primary Productivity:

- energy stored in biomass

- measurements

- factors affecting NPP

- light

- water

- temp

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

2. Net Primary Productivity:

- energy stored in biomass

- measurements

- factors affecting NPP

- light

- water

- temp

- nutrients

2. Net Primary Productivity:

- factors affecting NPP

- Nutrients: Nutrient Use Efficiency =

grams of dry mass produced/gram of nutrient absorbed

Lower NUE for a nutrient means it is more limiting (need more to produce the same biomass).

2. Net Primary Productivity:

- energy stored in biomass

- measurements

- factors affecting NPP

- light

- water

- temp

- nutrients

- Global Patterns

2. Net Primary Productivity:

- energy stored in biomass

- measurements

- factors affecting NPP

- light

- water

- temp

- nutrients

- Global Patterns

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

3. Net Secondary Productivity

- assimilations efficiencies – A/I

seed eaters: 60-80%

browsers: 30-40%

detritivores: 15%

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

3. Net Secondary Productivity

- assimilations efficiencies – A/I

seed eaters: 60-80%

browsers: 30-40%

detritivores: 15%

herbivores: 60-70%

carnivores: 80-90%

Low AE? Must eat more to get energy needed.

Horse – ‘hindgut ruminant’ – less efficient, high throughput

Cattle – ‘foregut ruminant’ – more efficient, can eat less.

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

3. Net Secondary Productivity

- affected by nutrient ratios, growth rates, and most limiting variable. May need to eat a lot to get enough of the limiting variable.

N:P :: 50:1

N:P :: 15:1

Fast growing; need higher ratio of Phosphorus for DNA synthesis.

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

3. Net Secondary Productivity

- Net Production Efficiency = P/A

What might this depend on???

NPP

NSP

Ecosystem Ecology

I. Introduction

II. Energy Flow

A. Productivity

3. Net Secondary Productivity

- net production efficiency = P/A

0.7%Shrews

0.5%Birds

6-10%MostMammals

Up to 75% for sedentary poikilotherms

Ecosystem Ecology

I. Introduction

II. Energy Flow

A.Productivity

B.Trophic Pyramids

Ecosystem Ecology

I. Introduction

II. Energy Flow

A.Productivity

B.Trophic Pyramids

- ecological efficiency: NSP/NPP (5-20%)

NPP of Producers (PLANTS)

NPP of HERBIVORES

Loss due to 2nd Law

NPP of Primary Carnivores

NPP of Secondary Carnivores

a. trophic "pyramids"

NPP of Producers (PLANTS)

NPP of HERBIVORES

Loss due to 2nd Law

NPP of Primary Carnivores

NPP of Secondary Carnivores

This is why large carnivores are RARE, and why they have large RANGES

Ecosystem Ecology

I. Introduction

II. Energy Flow

A.Productivity

B.Trophic Pyramids

C.Detrital Foodchains

Herbivores

Predators

Ecosystem Ecology

I. Introduction

II. Energy Flow

A.Productivity

B.Trophic Pyramids

C.Detrital Foodchains

HerbivoresNPPDetritivores

Temperate forest: 1.5% - 2.5%Old-field Habitat: 12%Plankton: 60-99%

Ecosystem Ecology

I. Introduction

II. Energy Flow

A.Productivity

B.Trophic Pyramids

C.Detrital Foodchains

D.‘Biomass Accumulation Ratios’

If we know the mean ‘standing crop’ of biomass from year to year, and we know the net productivity, we can calculate how long, on average the biomass persists:

BAR (per year) = (biomass/m2) / (np of biomass / m2 / yr)

Ecosystem Ecology

I. Introduction

II. Energy Flow

A.Productivity

B.Trophic Pyramids

C.Detrital Foodchains

D.‘Biomass Accumulation Ratios’

If we know the mean ‘standing crop’ of biomass from year to year, and we know the net productivity, we can calculate how long, on average the biomass persists:

BAR (per year) = (biomass/m2) / (np of biomass / m2 / yr)

Forests: ~ 20 years Tropical leaf litter: 3 monthsPhytoplantkon: ~20 days Temperate leaf litter: 2-20 years

Ecosystem Ecology

I. Introduction

II. Energy Flow

A.Productivity

B.Trophic Pyramids

C.Detrital Foodchains

D.BAR

E.Human Concerns

E. Human Concerns

E. Human Concerns

E. Human Concerns

E. Human Concerns

500% increase in 50 years, with population increase of 250%

E. Human Concerns

A doubling of meat production per capita

E. Human Concerns

25% of catch by weight discarded

E. Human Concerns

E. Human Concerns

6-10 lbs of feed for 1 lb increase in cattle weight2-5 lbs of fish meal for 1 lb increase in farmed fish weight

E. Human Concerns Edible kilocalories produced from kilocalories of energy required for cultivation are:

18.1% for chicken,

6.7% for grass-fed beef,

5.7% for farmed salmon

0.9% for shrimp.

123% for potatoes

250% for corn

415% for soy

input calories converted to calories able to be utilized by humans

So, for every 100 calories of energy we put in to raise chickens, we get 18 calories of energy produced in chicken meat. 100 cal into soy, 415 calories out.

E. Human Concerns

Food production, per capita(400 kg per year is healthy minimum)

SO HOW DID WE DO IT?

E. Human Concerns

EXTENSIFICATION – MORE AREA

E. Human Concerns

EXTENSIFICATION – MORE AREA

E. Human Concerns

The best land has already been used; further expansion in marginal areas is costly and requires more supplementation

E. Human Concerns

47% of historical forested land has been cut

E. Human Concerns

INTENSIFICATION

E. Human Concerns

E. Human Concerns

The best land has already been used; further expansion in marginal areas is costly and requires more supplementation

E. Human Concerns

Global NPP (dry mass) = 224 billion tons. 59% is terrestrial, and of this, humans 35-40% is controlled by humans, either eaten directly or fed to animals we will consume